[ios] Add flag ownership for gambard

iOS flag owners were asked to claim ownership and state an expiry in
this announcement email:
https://groups.google.com/a/google.com/g/bling-team/c/7YC_3l6yEzo/m/1-iZg1fPAAAJ

This is one of several CLs that adds iOS flag ownership information into
flag-metadata.json.

The owner of these flags was identified via git blame. A placeholder
expiry milestone of M86 was added. Please either LGTM, or suggest a new
owner and/or expiry.

Bug: 1058614
Change-Id: I049a1e16fcd8ad7e3e85343cc01ba028f201c2f1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095197
Commit-Queue: edchin <edchin@chromium.org>
Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748377}

chrome/browser/flag-metadata.json

@@ -869,6 +869,11 @@
     "owners": [ "shaktisahu", "qinmin" ],
     "expiry_milestone": 86
   },
+  {
+    "name": "drag_and_drop",
+    "owners": [ "//ios/chrome/browser/drag_and_drop/OWNERS" ],
+    "expiry_milestone": 86
+  },
   {
     "name": "drag-to-snap-in-clamshell-mode",
     "owners": [ "amusbach@chromium.org", "xdai@chromium.org" ],
@@ -2630,6 +2635,11 @@
     "owners": [ "joelhockey", "tbuckley" ],
     "expiry_milestone": 85
   },
+  {
+    "name": "mobile-google-srp",
+    "owners": [ "gambard" ],
+    "expiry_milestone": 86
+  },
   {
     "name": "mobile-identity-consistency",
     "owners": [ "bsazonov", "droger", "msarda" ],